1. Field of the Invention
The present invention relates generally to instant message systems, and more particularly to an instant message proxy that is capable of maintaining the availability status of a mobile subscriber when the communicating to the subscriber is temporarily broken.
2. Background of the Invention
Conventional instant message (IM) systems use a variety of system architectures. However, such systems typically require that potential IM participants, often referred to as buddies, must register and establish a connection with an IM login server. Participant-specific information, such as presence contact information, is generated through this registration and is stored in a database associated with the IM login server for the duration of the IM session. Additionally, the IM login server uses the connection to determine the presence status of the buddy; if the connection is broken, the buddy is unavailable. Once IM participants are registered with the IM login server, messages sent between registered participants are typically routed through an IM message server or servers to the respective designated target buddy or buddies.
The above-described conventional IM systems have certain associated limitations when one or more of the participants in an IM session communicate via an IM-enabled mobile station such as a mobile handset. Specifically, IM systems typically rely on a best-effort delivery mechanism in which a message intended for a target buddy is delivered if the IM login server determines that the target buddy is available. If the IM login server determines that the target buddy is not available, the message is dropped. Because a mobile station participant may move in and out of service during an IM session, it may not be possible for the mobile station to maintain a reliable connection with the login server. If the connection is lost, messages targeted at the mobile station will be inadvertently dropped.
In addition, a circuit-switched mobile network has both a considerable delay associated with an IM connection set-up and a high cost associated with maintaining an open connection during an IM session. Therefore, it is not economically practical to implement an IM system with mobile network subscribers by establishing and then maintaining open connections for the duration of IM sessions.